CORE C - SUMMARY/ABSTRACT The Imaging Core (c) will provide services and expertise to all PPG investigators in designing and executing imaging experiments required to meet the objectives of each project. This core will be used by all three scientific projects. Core personnel will 1) advise and assist all PPG participants in the design and execution of all imaging experiments; 2) process all tissues and cut all sections required; 3) assist or directly perform all imaging experiments needed; 4) assist or directly perform all imaging data analyses and interpretation; 5) facilitate archiving and retrieval of imaging data. Investigators will be advised of the full potential of the Core's capabilities to ensure that experimental designs fully utilize the facility. State-of-the-art techniques available in the Core include Single Photon Emission Computed Tomography combined with X-ray CT (CT-SPECT) for whole-body imaging, intravital microscopy (IVM) and immunohistochemistry (IHC) and immunofluorescence (IF) for imaging at the tissue and cell levels, and electron microscopy (EM) for imaging at the subcellular level. Each of our imaging modalities described below is well-suited to focus on a specific aspect of targeting and processing. The multiple imaging approaches provided by the Core will complement and confirm one another and will provide a more complete analysis of targeting and processing in vivo at multiple levels. Data acquired via the services provided by this Core include: 1) validating APP2 expression by examining tissue sections using histochemical and fluorescence- based assays 2) defining and quantifying lung EC targeting by APP2 antibodies over time using dynamic whole-body imaging; 3) evaluating and quantifying EC processing of targeted APP2 antibodies, immunocomplexes and NP conjugates via dynamic IVM; 4) assessing by EM the targeting and processing of APP antibodies, immunocomplexes and NP conjugates at the cellular and subcellular levels. The Core will help answer key questions on the distribution of APP2 in human tissues, on how the lung processes specific probes in vivo and how caveolae function in the endothelium of the lung in vivo both in rodent and human tissues. Data acquired will be stored on the PRISM server and links to all images will be available via Accessible VAscular TARgets database (AVATAR), an in-house relational protein database (see Administrative Core for details).